The economical and rapid distribution of raw materials and finished goods is of the utmost importance. Trucks are components of many distribution systems, and a very common type of truck is the tractor-trailer combination or "semi" as it is often called. The trailer of a tractor-trailer combination will henceforth be referred to as a trailer or "semi-trailer," and a semi-trailer generally includes an open or closed towable body and at least one set of wheels for supporting the trailer body. Other types of trucks are also used in distribution systems, and each type of truck generally includes a body that is supported by at least one set of wheels: For the most part, the following description is directed to tractor-trailer combinations, though the invention may be used with many types of trucks. Thus, when the term trailer or semi-trailer is employed, it should be interpreted to include truck bodies generally.
As one component of a distribution system, a semi-trailer must be loaded and unloaded at various locations. One loading/unloading method involves the use of a "dock" which may be open but is sometimes sized to enclose only the rear end of a semi-trailer, and into which the entire semi-trailer cannot be driven. Docks often include "seals" which seal against the top, bottom and side surfaces of the semi-trailer body to limit air exchange between outside and inside the building. For example, U.S. Pat. No. 3,665,997, issued to V. O. Smith and A. T. Dietrich, shows a dockseal assembly having a flexible headseal for engaging the top surface of a trailer body. Similarly, U.S. Pat. No. 4,213,279, issued to R. C. Layne, discloses a dockseal that seals against the top, bottom and side surfaces of a trailer body.
Semi-trailers are also used in conjunction with warehouses in some distribution systems. Warehouse operations often involve driving the trailer through an opening in one of the outside walls of a building and into its interior. With the trailer so positioned within the warehouse, it may be said that the warehouse "houses" the trailer even though the trailer may not be completely contained within the outside walls of the building. Since warehouse loading and unloading is done through the rear doors of a semi-trailer, it is not necessary to bring the entire semi-trailer within the building. In other words, a portion of the trailer may in fact lie outside of the building, and sealing the space between the trailer body and the outside wall and floor of the building becomes a problem.
From time to time any semi-trailer will require mechanical repairs or upgrades. Such maintenance is typically performed in a service building or garage that is designed to accommodate several trailers, often in two rows of bays, as shown in FIG. 1, a top plan view of such a building, with its roof removed and with several semi-trailers within the building. A semi-trailer can be backed into a bay so that its running gear (i.e., wheels, brakes, etc.) is more accessible. A trailer can also be pulled into a bay with its running gear adjacent to the service bay door to permit, for example, work on an air conditioning unit mounted on the front surface of the trailer. In either event, when two trailers are positioned in opposing bays such that the longitudinal axes of the semi-trailers are substantially colinear, a working space W.sub.x is created between the trailers. The subscript x corresponds to the Figure number. The longitudinal axis of a semi-trailer body is herein defined as an axis that passes lengthwise through a semi-trailer and is substantially perpendicular to the front and rear surfaces of the semi-trailer. Is is this working space W.sub.x that the workers must share, and the work might include welding on one trailer and the charging of an air conditioning system on another trailer. In fact, most of the repair and modification work is performed on the front or rear end of a semi-trailer, the particular end being serviced typically being located adjacent to the working space W.sub.x. It is thus imperative that there be enough working space W.sub.x so that the workers do not interfere with one another to minimize the danger of accidents.
Many service buildings were designed and built to accommodate trailers having a length of 40 feet, the maximum length formerly allowable. The trailer length is designated with an R.sub.x in the accompanying figures. In these buildings, the working space W.sub.x between bays was made large enough to safely accommodate most maintenance tasks on 40 foot trailers. For example, a typical service building was 100 feet wide, thus permitting the working space W.sub.x to be as large as approximately 20 feet. FIG. 1, not to scale, represents this situation, with W.sub.1 being approximately 20 feet, R.sub.1 being approximately 40 feet, and L, the width of the service building, being approximately 100 feet.
Regulations have been relaxed, however, to permit longer trailers. Forty-eight foot trailers are presently acceptable and are becoming more commonplace, particularly due to the ability to "stretch" semi-trailers in length, an upgrade operation performed on a shorter semi-trailer. It is possible that even longer trailers will be allowed in the future, considering escalating energy costs. Longer trailers result in a smaller working space W.sub.x when a standard service building is used, as shown in FIG. 2, a top plan view of a 100 foot wide building containing a plurality of longer semi-trailers. For example, if a 100 foot building contained two axially-aligned longer trailers, each 48 feet long, less than 4 feet between trailers would remain, an undesirable situation.
Thus, there exist at least two problems with the use of semi-trailers in typical distribution systems. First, when a semi-trailer is used in the context of a warehouse situation where the semi-trailer is backed through an opening in an outside wall of building but is not entirely contained within the building, there are the problems of sealing out the elements and maintaining security so that the goods within the warehouse and semi-trailer may be protected. And secondly, particularly in light of longer semi-trailers, existing service buildings are often too short to permit safe and efficient simultaneous servicing of two longer semi-trailers in opposing service bays.
With respect to the second problem cited above, i.e., inadequate service buildings, several "solutions" have been proposed. One proposal, obviously uneconomical in most cases, is to erect new service buildings. The new buildings could be made long enough to accommodate two 48-foot trailers, but again it is possible that even longer trailers will be allowable in the future.
Another proposed solution to the service building problem discussed above is to extend pre-existing service buildings. Again, such a "solution" involves large capital expenditure and is simply unworkable in many cases. Still another disadvantageous approach is to retain existing buildings but not simultaneously accomodate longer semi-trailers in opposing bays. As longer, perhaps "stretched," semi-trailers are becoming more and more prevalent, such a limitation would have a deleterious effect on a service organization's business.
Another proposal is to simply allow the ends of the semi-trailers to extend through the door openings, thus effectively precluding a complete enclosure of the semi-trailers and the interior of the service building. Such a practice would result in a situation analogous to the warehouse operations discussed above where a portion of the semi-trailer protrudes through an opening in the outside wall of the building, and in both cases there are the problems of security risks, energy loss and discomfort to the workers within the building during periods of inclement weather.
Each of the proposed solutions mentioned above possesses shortcomings. The first three solutions, i.e., a new building, an extension to the old building and the limitation on use of opposing bays, are all potentially quite costly. The fourth solution, allowing the semi-trailers to extend through openings in the outside wall, presents security, energy loss, and comfort problems.
The present invention is directed to the short-comings possessed by the proposed solutions discussed above. Particularly, the invention allows the occupant of a building, whether it be a warehouse or a service building, to utilize the building without having to erect another building and without having to extend the building. Thus, capital funds are conserved and construction delays are avoided. The present invention also allows the operator to use all of the bays within his building regardless of the lengths of the semi-trailers. Importantly, particularly in the service building situation, the present invention completely encloses the interior of the building yet permits a large working space W.sub.x to create a better working environment for the service personnel.